Dual electrostrictive drivers bonded to and driving opposite sides of mechanical resonator



Aug. 2, 1966 w. POSCHENRIEDER 3,264,585

DUAL ELECTROSTRICTIVE DRIVERS BONDED TO AND DRIVING OPPOSITE SIDES 0FMECHANICAL RESONATOR Filed June 5, 1962 United States Patent DUALELECTROSTRICTIVE DRIVERS BONDED TO AND DRIVING OPPOSETE SIDES OFMECHANI- CAL RESONATOR Werner Poschenrieder, Munich, Germany, assignorto Siemens & Halske Aktiengesellschaft, Berlin and Mnnich, Germany, acorporation of Germany Filed .Tune 5, 1962, Ser. No. 200,255

Claims priority, application Germany, June 20, 1961,

2 Claims. (a. 333-72 The invention disclosed herein is concerned with anelectrostrictive coupling arrangement for a resonator performingoscillations according to the longitudinal mode, such resonator beingmade preponderantly of material which is inactive in electrostrictivesense, especially of a metal, preferably steel, the remaining resonatorparts being made of electrostrictive material, especially ceramicmaterial which is active in electrostrictive sense and provided withenergizing or triggering electrodes.

Coupling arrangements of this general kind, for longitudinaloscillators, are described in the copending application Serial No.91,215, filed February 23, 1961, owned by the assignee also named in thepresent case.

The object of the present invention is to improve the prior structure byforming the resonator as a fiat strip made of material which is inactivein electrostrictive sense, such strip being inthe region of the zonewhich is neutral for longitudinal oscillations, provided on both sidesthereof with flat layers of electrostrictive material coveringpreferably only part of the resonator length, and disposing upon eachside of the respective layers, which faces away from the resonator, anenergizing or triggering electrode serving for feeding in identicalphase the parts which are active in electrostrictive sense with respectto the resonator proper.

Details of the invention will appear from the description which isrendered below with reference to the accompanying drawing showing anembodiment thereof.

The drawing shows an electromechanical filter comprising threelongitudinal oscillators 1, 2 and 3. These longitudinal oscillatorswhich are of flat configuration, are interconnected by coupling bridgesin the manner described in the previously noted copending application.

The coupling arrangement according to the present invention is providedrespectively at the input and the output sides of the filter formed bythe longitudinal oscillators. It comprises two thin plates 4, 5 ofelectrostrictive ceramic material which are soldered to the respectivelongitudinal oscillators 1 and 3, made preferably of steel,symmetrically with respect to the neutral zone thereof which isindicated by a dot-dash line. The sides of the plates 4 and 5, made ofelectrostrictive material, which face away from the steel resonator, aremetallized. Each metallized side is provided with a lead-in wire such asindicated at 6 and 7, which extends therefrom preferably in the regionof the neutral zone. A further leading wire 8 extends from therespective longitudinal oscillators,

Patented August 2, 1966 "ice which are made of steel, at points whichare suitably likewise placed in the region of the neutral zone. However,the further lead-in wires may also be placed outside of such region.

The respective two lead-in wires 6 and 7, which are mutuallyinterconnected, serve as terminals for the energizing or triggeringelectrodes of the ceramic plates 4 and 5 with respect to the metallicresonator bodies 1 and 3. Accordingly, there is effected a phased feedfor the energizing or triggering devices disposed upon the two sides ofthe resonator. This results in triggering which is the more positive anddefinite the more uniform the ceramic parts are which are being used.This will be understood upon considering that the individual ceramicplate will attempt to excite the respective longitudinal oscillator to abending oscillation which is, however, made impossible due to the factthat the bending components of the two triggering devices of theindividual coupling arrangement are mutually cancelled, thus resultingin a pure longitudinal excitation.

The steel body which is made of one piece can of course form more orfewer than three resonators.

Changes may be made within the scope and spirit of the appended claimswhich define what is believed to be new and desired to have protected byLetters Patent.

I claim:

1. A resonator for executing longitudinal oscillations, comprising agenerally fiat strip made of material which is inactive inelectrostrictive sense and forms the resonator proper, and anelectrostrictive coupling arrangement, comprising a pair ofsubstantially identical flat layers made of electrostrictive material,each of which is disposed at a respective side of said strip in theregion of the zone which is neutral for longitudinal oscillations, saidlayers coextensively covering opposite sides of said strip only for partof its length, each layer being provided with a triggering electrodeupon the side thereof which faces away from said strip, and means forutilizing said triggering electrodes for feeding in identical phase theparts which are active in electrostrictive sense with respect to theresonator proper.

2. A resonator according to claim 1, wherein said strip is made ofsteel, said layers being formed of electrostrictive ceramic material,each layer being metallized on the side thereof which faces away fromsaid strip and which form the respective triggering electrodes.

References Cited by the Examiner UNITED STATES PATENTS 2,695,357 11/1954Douley 33372 2,814,785 11/1957 Burns 33371 3,015,789 1/1962 Honda 333-713,064,213 11/1962 Mason 333-71 3,086,183 4/1963 SChOfer 33372 HERMANKARL SAALBACH, Primary Examiner.

C. BARAFF, Assistant Examiner.

1. A RESONATOR FOR EXECUTING LONGITUDINAL OSCILLATIONS, COMPRISING AGENERALLY FLAT STRIP MADE OF MATERIAL WHICH IS IN ELECTROSTRICTIVE SENSEAND FORMS THE RESONATOR PROPER, AND AN ELECTROSTRICTIVE FOUPLINGARRANGEMENT, COMPRISING A PAIR OF SUBSTANTIALLY IDENTICAL FLAT LAYERSMADE OF ELECTROSTRICTIVE MATERIAL, EACH OF WHICH IS DISPOSED AT ARESPECTIVE SIDE OF SAID STRIP IN THE REGION OF THE ZONE WHICH IS NEUTRALFOR LONGITUDINAL OSCILLATIONS, SAID LAYERS COEXTENSIVELY COVERINGOPPOSITE SIDES OF SAID STRIP ONLY FOR PART OF ITS LENGTH, EACH LAYERBEING PROVIDED WITH A TRIGGERING ELECTRODE UPON THE SIDE THEREOF WHICHFACES AWAY FROM SAID STRIP, AND MEANS FOR UTILIZING SAID TRIGGERINGELECTRODES FOR FEEDING IN IDENTICAL PHASE THE PARTS WHICH ARE ACTIVE INELECTROSTRICTIVE SENSE WITH RESPECT TO THE RESONATOR PROPER.